16:9 widescreen

What is 16:9 widescreen?

16:9 is the widescreen format that the world has standardized on for
future
HDTV services. It has also been used in the NHK 1125-line analog HDTV
standard
and the Eureka 1250-line HDTV standard, as well as variety of enhanced
SDTV (standard-definition TV) services in Europe and Japan. The screen
is 16 units wide by 9 units high, so the "aspect ratio" is called 16:9
because it's easier to remember than 1.78:1 (approximately) which is
the
"normalized" number.

Currently, most SDTV in the world is 4:3 (which equals 12:9,
or 1.33:1). 35mm motion pictures are typically 1.66:1 (European),
1.85:1 (American) or
2:39:1 (anamorphic;
adopted by SMPTE in 1971; hides projectionist's splices a bit better
than
the previous standard of 2:35:1) although a bewildering variety of
aspect
ratios has been used at one time or another.

Why should I care about 16:9?

As the world slowly and painfully switches over to digital
broadcasting,
it looks to be a 16:9 world we're all moving into. Although it's likely
to take ten years or more before 16:9 receivers outnumber 4:3 receivers
worldwide, and there will always be a huge legacy of 4:3 SDTV programs
in the vaults, "premium" programming in the future will almost
certainly
be 16:9 material, in both "standard definition" and "high definition"
forms.

4:3 program material won't be obsoleted by any means, but
many forward-looking
producers are composing and shooting for 16:9 to maintain as high a
value
as possible for all future distribution possibilities. Some are
actually
shooting 16:9, while others are practicing "shoot and protect" in 4:3,
just by making sure that the material can be cropped to 16:9 without
losing
any important content from the top or bottom of the image.

How do you get 16:9 pictures?

You can use the 16:9 switch on your camera (if it has one). Or, you can
shoot and protect a 16:9 picture on 4:3. Or, you can use an anamorphic
lens.

Many cameras have a 16:9 switch, which
when activated results
in either a "letterboxed" image and/or an anamorphically-stretched
image.
But be careful; there's a right way and a wrong way to do this.

The "right way" is to use a 16:9 CCD. When in 4:3 mode, the
camera ignores
the "side panels" of the CCD, and reads a 4:3 image from the center
portion
of the chip. When in 16:9 mode, the entire chip is used. In either
case,
the same number of scanlines is used: 480 (525/59.94 DV) or 576
(625/50
DV). You can tell when a camera is capturing 16:9 the "right way"
because
when you throw the switch, whether the resultant image is letterboxed
in
the finder or squashed, a wider angle of view horizontally is shown,
whereas
the same vertical angle of view is present.

The "wrong way" is for the camera to simply chop off the top
and bottom
scanlines of the image to get the widescreen picture. When you throw
the
switch on these cameras, the horizontal angle of view doesn't change,
but
the image is cropped at the top and bottom compared to the 4:3 image
(it
may then be digitally stretched to fill the screen, but only 75% of
the
actual original scanlines are being used).

[There are some Philips switchable cameras that do clever
tricks with
subdivided pixels on the CCDs; when you flip into 16:9 mode, the
image's
angle of view will get wider horizontally and
tighter vertically.
So to really be sure, use the change -- or lack thereof -- in the horizontal
angle of view to see if your camera is doing 16:9 "the right way".]

[Some Digital8 and DV cameras, like the PDX10, seem to split the
difference: when in
16:9, the
picture gets slightly cropped on top and bottom, and
it gets a little
wider! They seem to be
using some extra chip area normally used for digital image
stabilization
to go wider, yet they don't have a wide enough CCD for true 16:9.]

The "wrong way" is wrong because the resultant image only
uses 360
lines (525/59.94) or 432 lines (625/50) of the CCD instead of the
entire
480 or 576. When this is displayed anamorphically on your monitor, the
camera has digitally rescaled the lines to fit the entire raster, but
1/4 of the vertical resolution has been irretrievably lost, and the
in-camera algorithms
used to stretch the image often create ugly sampling artifacts. This
is
not
too terrible for SDTV playback (still, it isn't great), but it's
asking
for
disaster if the image is upconverted to HDTV or film (Soderburgh's
"Full
Frontal" is prime example of the perils of in-camera vertical
stretch).

The bad news is that most inexpensive DV cameras (including
the VX2000
and XL-1s) do 16:9 the wrong way.

[Note that there are two "wrong ways," the
vertical-pixel-shift method
used by Canon and Panasonic, which isn't quite as bad as I make it
sound; and
the field-doubled/interpolated method employed by Sony (I don't know
what
JVC does). The Canon/Panasonic method yields images softer than true
16:9,
but cleaner and sharper than the Sony method. I discuss the
differences
in more detail a bit further on.]

16:9 chips were very costly and the
yields (and demand) were low at the turn of the century; in late '98
Sony's DXC-D30WS 16:9-capable
DSP camera (which, docked with the DSR-1 DVCAM deck, became the
DXC-D130WS
camcorder) was only available in short supply, and the Sony sales
force
was encouraged to steer folks to the non-widescreen D30 model unless
they
really needed widescreen, because the supplies were
so limited.
Even then, the WS model commanded a US$3000 premium over its 4:3-only
sibling.

By 2005, things were a lot better. Canon's XL2 was the current
entry-level
true 16:9 camera in any of the DV formats. Many low-cost HDV and
DVCPROHD cameras with true
16:9 sensors also record DV (and DVCAM or DVCPRO50) in 16:9 mode. At
the low end, the single-chip CMOS Sony HDR-HC1 shoots 16:9 for under
$2000; at the high end, cameras like the Canon's XL H1 (DV and HDV)
and
Panasonic's AG-HVX200 (DV, DVCPRO50, and DVCPROHD) shoot 16:9 for
under
$10,000.

An anamorphic lens is the way film folks
have done widescreen
for years. A cylindrical element squashes the image laterally, so that
you get tall, skinny pictures like images in a fun-house mirror. This
squashing
allows the 16:9 image to fit in the 4:3 frame. Century
Precision
Optics has anamorphic
adapters to fit the VX1000, DSR-200, VX2000, PD150, GL1, and
similar
camcorders, as does Optex
(distributed in the USA by ZGC).
Both
allow you to use the wider half of the zoom range, and both run
about
US$800.

In the film theatre, or in the film print lab, a similar
anamorphic
lens unsquashes the image to yield the original widescreen image. In
video,
you use a DVE or an NLE plug-in filter to unsquash the image for
letterboxed
output, or you embed the appropriate codes into the data stream or
video
image (the codes differ in specification between different broadcast
standards)
to tell the receiver that the image should be displayed as widescreen.
Most DV NLEs that support widescreen production, including Premiere
6.0,
Final Cut Pro 1.2.5 and later, EditDV 2.0, and CineStream, insert this
code when you specify a 16:9 aspect ratio.

Anamorphics come with their own problems; they tend to be on the
soft side, and they're limited in the focal ranges and focal distances
at which they give a satisfactory image. They effectively work as
wide-angle lenses in the horizontal direction only; as a result, they
tend to focus differently in the horizontal and vertical directions!
Color fringing and general softening tend to be problems,
too. Still, anamorphics can be worth the effort if you're willing
to work within their limits, and their bokeh (the pattern of fuzziness
of out-of-focus areas) and flare are very distinctive. Anamorphics
have
a different "look" than "flat" lenses, and sometimes that look is
just what you want.

And if you don't have a true
16:9 camera and can't find an
anamorphic
lens? First, try using a 4:3 Canon or Panasonic camera; as explained
below,
they do a better-than-expected job in 16:9.

Otherwise, Shoot and protect 16:9 on
4:3. Use the entire, non-widescreen
4:3 image, but protect your future revenue streams by ensuring that
all
important visual information is contained vertically in the center or
upper
3/4 of the screen. That way you have the full resolution 4:3 image for
use today, and you can always upconvert to HDTV later in the 4:3
aspect
ratio or the 16:9 aspect ratio if you can accept
the reduced vertical
resolution. Should you need to repurpose the material into a 16:9 SDTV
format later, you can letterbox it in post by setting up a vertical
shutter
wipe, putting black bands at the top and bottom of the screen just
like
on MTV.

You're no worse off than with 16:9 material shot "the wrong
way", but
you have the freedom and flexibility of a full-resolution 4:3 image
that's
compatible with today's broadcast and non-broadcast standards.

Or are you? Since the
"wrong way" digitally stretches
the image prior to DV compression, the DV codec doesn't have to
compress
the "wasted" material at the top and bottom of the 4:3 image. As a
result,
those central 360 (or 432) lines are spread out over the entire height
of the picture, and all the DCT blocks are employed in compressing
useful
bits of the image. As a result, slightly more vertical resolution is
preserved
through the compression process when shooting the "wrong way" vs.
"shoot
and protect". Ben Syverson has pix
that show the difference.

Unfortunately, only the Canons and Panasonics look as good
as Ben's
pictures show. These cameras employ "pseudo-frame" resampling courtesy
of vertical pixel shift, in the same way they get decent frame
mode
images. As a result, the images have more vertical
resolution
than purely field-based resampling provides, even if they aren't as
good
as using an anamorphic or a true 16:9 CCD.

Sonys do a much poorer job of fake 16:9; they look
equivalent to performing
the same resampling in a field-based NLE like Final Cut Pro, with an
added
and excessive vertical edge enhancement used in a losing battle to
retain
perceived sharpness.

Fake 16x9 from a Canon XL1 or GL1, or a Panasonic AG-EZ1,
AJ-D200
series,
or the like.

4:3 cropped and stretched in post using an NLE.

Fake 16x9 shot on a 4x3 Sony.

Mind you, this ranking does not take into account the fundamental
quality
differences in the different camera heads and lenses. I'm only
discussing
the relative qualities of the different means of generating a 16:9
image
in what's still largely a 4:3 world.

Frame mode, slow shutters,
and "the film look"

What is this "frame mode" I hear so much about?

Several cameras, including the Panasonic AG-EZ1 and AJ-D200/210/215 and
the Canon XL1, XL1s, GL1, GL2, XM1, and XM2, have a "frame movie mode"
or "frame mode" switch
that
changes the way the CCD is read out into buffer memory from interlaced
to progressive scanning. This gives a 30 fps "film look" frame-based
image
instead of the 60 fps field-based image we normally see on TV.

Each video frame shows up as an intact frame-based image in
which both
the even and odd fields have been captured at exactly the same
time with no interlacing artifacts (of course, the data stream written
to tape still interleaves the
even and odd fields for proper interlaced TV display; it's just that
both
fields have been captured simultaneously instead of in even-odd
alternation). When shown
on TV, frame mode images have had their temporal resolution reduced by
half to 30 fps, fairly close to film's 24 fps. For the 625/50 XL1s
sold
in PAL countries, the 25fps video frame rate will make for an even
closer
match.

This is useful for those looking for a more "film-like"
motion rendering
while staying in video. Independent documentry filmmaker Sam Burbank
shoots
most of his stuff for National Geographic in Frame Movie Mode on his
Canon
XL1, and reports that DigiBeta shooters see his stuff in editing and
say,
"there you go, making us look bad by shooting film"!

These cameras get their "proscan" images not by truly
perfoming progressive
readout on the chips, but rather by offsetting the green CCD's read
timing
by one scanline during readout -- vertical pixel-shift, if you will.
In
essence, an even field from R & B CCDs is blended with an odd
field
from the G CCD, giving you a frame that has the scanlines for both
fields
captured at the same instant in time. This gives a definite
improvement
over mere field-doubled "frames", but it's not as sharp vertically as
true
proscan. Each "scanline" is actually composed of two scanlines from
each
chip, so there is some softening vertically; also, the effective
chroma
resolution
is halved vertically. My Technical Difficulties article "Frames
and
Fields" goes into a lot more detail on the
topic.

Current Sonys, alas, do not do nearly as well. They have a
true proscan
mode, but only at half the normal frame rate (15 fps NTSC, 12.5 fps
PAL).
Setting the Sonys into slow shutter speeds appears to work, but only
on
the half-resolution LCD viewscreens; the recorded image is
line-doubled,
and quite noticeable "jaggy" and inferior.

Of course, the Panasonic
AG-DVX100 shoots both 30P and 24P (NTSC: 25P only in PAL)
with a true progressive CCD, as does the Canon XL2 and the
Panasonic AG-HVX200.

How do I get "film look" shooting with DV
cameras?

Buy a used Arriflex 16BL or CP GSMO, stencil "Canon XL1 DV camcorder"
on
the side, and shoot film!

Seriously, though, the most important way to get a filmlike
look is
to shoot film style. Light
scenes, don't just go
with whatever light
is there. Use lockdowns or dolly shots, not zooms. Pan and tilt
sparingly
to avoid motion judder (i.e., if you're using the XL1's frame mode,
you
shouldn't compose any shot to call attention to the 30 fps motion
rendering).
If you're using a camera that allows it (most prosumer 3-chip
camcorders, pro cameras), back down the "detail" or "sharpness"
control.
Reduce chroma slightly. Lock the exposure; don't let it drift. Use
wide
apertures, selective focus, and "layered" lighting to separate
subjects
from the background. Pay attention to sound quality. In post, stick
mostly
to fades, cuts, and dissolves; avoid gimmicky wipes and DVE moves.

The Panasonic
AG-DVX100 and AJ-SDX900 and the Canon XL2 DV camcorders record a
24
fps image using 3-2 or 2-3-3-2
pulldown on
regular DV tape; it gives you the same motion sampling
as
motion picture film, undeniably part of the "film look". Many
higher-end professional Sony DVCAM camcorders acquired 24p modes as of
2005. Beyond that,
you
can use "frame mode" on the Canon XL1/XL1s/GL1/GL2/XM1/XM2, Panasonic
AG-EZ1, or AJ-D215; try
15
or 30 fps on the VX1000. On the Sony it's not the same as frame mode
and
has other problems, but it may pass as film's motion rendering for
some
purposes. In HD, the JVC GY-HD100, Panasonic AG-HVX200 and HDC27
Varicam, and the Sony HDW-F900 CineAlta, as well as Sony's XDCAM HD
and
GVG's Infinity camcorders, have 24p modes.

On higher-end cameras (DSR-300, DSR-130, AJ-D700, and the
like), as well as some of the better prosumer camcorders, you
may have setup files to adjust gamma, clipping, sharpness, color
rendition,
and white compression (knee); these can be exploited to give the
camera
a more
filmlike transfer characteristic.

Take the aperture correction (edge enhancement or sharpness
setting),
if available, and turn it down or off. This also makes a huge
difference
both in film transfer and in HDTV upconversion.

Try out the Tiffen Pro-Mist filters. I like the Black
Pro-Mist #1 or
lower (fractional numbers). Jan Crittenden at Panasonic prefers the
Warm
Pro-Mist 1/2, while others prefer the Tiffen Glimmerglass series.
These
knock off a bit of high-frequency detail and add a
bit of halation around highlights. Bonus: by fuzzing the light around
bright,
sharp transitions, these filters have the added effect of reducing
hard-to-compress
high-contrast edges, resulting in fewer "mosquito noise" artifacts.

In post, there are a variety of filters or processes
available to adjust
the gamma and extend the red response; simulate 3-2 pulldown of 24fps
imagery from 60i sources; add gate weave,
dust and scratches, film fogging; and so on.

The hot one as of mid-2002 is Magic
Bullet,
an After Effects plug-in also usable in many NLEs. It was developed
internally
at high-end post house The Orphanage, then packaged for the unwashed
masses such as
you and me. ToolFarm,
which stocks
a variety of useful postproduction applications, is the exclusive
distributor.
You can download both the manual and a free demo version: just like
the
local
drug dealer says, "the first hit is free..." <grin>.

In December 1999, Jeffrey Townsend of The Fancy Logo Company
wrote me
and said:

...and I have only one thought to add (so
far): In
your section on getting a film look on video, you should consider
referencing
the DigiEffects
product "CineLook," which was created as an Adobe After Effects
plug-in,
but works great with Final Cut Pro. I almost didn't want to
write
this note, because I'd just as soon not have everybody know about
this
incredible cheat. It's gonna kill the terrific black-box
technology
called FilmLook, because it's so capable, so flexible, and easily as
successful
in doing what it's supposed to do.

I promise I don't work for
DigiEffects. I've just gotten going
on a Final Cut Pro/Canon XL-1 based production studio, and just
rendered
three commercials with CineLook (after doing exactly what you
describe,
lighting as though it was film), and I swear it looks like
something
between
superbly transferred 16mm and an ordinary transfer of 35mm.
And I'm
still in my first week of playing with it! I don't even know
how
to get the most out of it...

I've never seen such an enthusiastic endorsement before, but it tracks
other things I've heard about CineLook. They've got a companion
product,
CineMotion, for faking 3:2 pulldown. They've got packages for Mac, PC,
and Unix systems. The DigiEffects stuff isn't cheap, but it would
appear
to be worth it (and no, I don't work for DigiEffects, either!).

John Jackman writes that a company called BigFX
makes a $500
FilmFX
plug-in that's faster than CineLook and does a passable job.

Keith Johnson of Xentrik
Films
& Software was planning on a plug-in called
FliXen, but that
project seems to have fallen by the wayside.

Ned Nurk worked on a standalone processor for Windows called
FilmRender (formerly
FilmMunge), which batch-processed AVI files. It was by all accounts
good,
fast, and very affordable. Unfortunately some slimeball crackers
hacked
his authentication system and pirated it. As a result, Ned stopped
development
and sales, and the DV world lost a useful tool. Think
about that
the next time you decide to "borrow" some software!

There are also proprietary processes such as "FilmLook"
that,
for a
price of around $95/minute, makes the video look so film-like that
real
film looks like video by comparison (joke. Well, at least a little).

Andy Somers has more useful info at VideoLikeFilm,
along with his own process "Feature Look".

Of course, if you really wanted film, why didn't you shoot
film? :-)

What do the slow shutter speeds do for me?

The slow shutter speeds (those below 60 fps) found on many DV cameras
use
the digital frame buffer of the camera in conjunction with a variable
clock
on the CCDs to accumulate more than a field's worth of light on the
face
of the chip before transferring the image to the buffer and thence to
tape.
This can do two things for you: more light integration, and slower
frame
update rates.

More light integration means that you can get usable images
in lower
light than you might expect. I've shot sea turtles by moonlight at
midnight
at 1/4 sec shutter speed; the images update slowly but are certainly
recognizable,
whereas the same scene at 60 fps looked like I had left the lens cap
on.

You can also use the long shutter times as a poor man's
"clear scan"
for recording computer monitors without flicker. As you increase the
integration
time on the CCD, the computer monitor goes through more complete
cycles
before the image is transferred, reducing recorded flicker; many
computer
images have little motion so the slow update rate may not even be
noticed.
Be aware, however, that at least some cameras (the Sony VX1000 among
them)
appear to go into a strange field-doubling mode at shutter speeds
below
60; vertical resolution is cut in half (while two clearly-interlaced
fields
are recorded on tape, as can be seen in a NLE, the field-mode flag is
set
in the DV datastream so that field-doubling is performed by the DV
codec
during playback to eliminate interfield flicker) so fine detail will
be
impaired. You'll need to judge this tradeoff on a case-by-case basis.

Slower frame update rates are good for two things: a poor
man's "film
look" at 30 fps or 15 fps, and special effects at slower rates. You
can
capture a strobing, strangely disturbing image at the lower rates...
use
it sparingly, of course; no sense in annoying your viewers.

Those funny free-spinning lens
controls

Why don't consumer DV cameras have "real" lenses
with focus marks?

"Real" lenses use helical grooves to rack focus; the resistance you
feel
when you focus such a lens is the natural friction of the rotating
barrels
sliding through the lightly-greased grooves.

That smooth friction, alas, plays havoc with autofocus
systems which
all consumer cameras must have, so goes the
conventional wisdom;
strong and battery-draining motors are needed to spin such barrels,
and
they can't obtain the fast focus response that's so useful in
optimizing
autofocus algorithms.

Thus autofocus lenses use lighter, more easily positioned
internal focusing elements (which are also advantageous from an
optical
standpoint) with lighter, faster, more thrifty focus servos.

The "focus ring" you manhandle isn't actually connected to
the focusing
mechanism. It's a free-spinning ring with an optical or
electromagnetic
sensor attached: when you spin the ring, a series of pulses is sent to
the focus controller. The faster the pulse train, the faster the
controller
changes focus.

However, it's not perfectly linear. If you turn the ring too
slowly,
nothing at all will happen since the controller discards all pulses
below
a certain rate as random noise. If you spin it 1/4 turn very quickly,
you'll
get more of a focus shift that if you turn it 1/4 turn at a more
moderate
rate.

As a result of all of this, there's no way for the focus
ring to have
focus marks -- nor is it possible for you to measure such marks
yourself
and be able to repeat them.

The same argument applies to the zoom controls on some
lenses, such
as the 16:1 and 3:1 zooms on the Canon XL1 or the zoom rings on the
Sony VX2000 and PD150.

How do I work with these lenses?

Carefully, with patience and understanding. You can't set marks, or
focus
by scale. Slow, fine adjustments may do nothing. But with practice and
perhaps some adjustment of operating style, most people can use if not
necessarily love these lenses.

On the XL-1, you'll get better zoom control and smoother
operations
if you stick to the zoom rocker on the handgrip than if you use the
zoom
ring on the lens. Some folks are taping over the zoom ring entirely
and
only using the rocker.

I find the zoom rings on the VX2000, PD150, and DSR-250 to
be superb,
almost as good as a "real" zoom control. You still can't set marks
with
them, but they're good enough for slow ramps and smooth accelerations.

Don't like it? Buy a real camera with a real
lens, like the Sony DSR-300 (US$8,000 and up, with lens) or the
Panasonic AG-DVC200
(US$6,000 or so) or the JVC GY-DV5000 (US$5,000 with lens). Hey, it's
only
money...

Image Stabilization

What's EIS/DIS?

Electronic Image Stabilization
and Digital Image Stabilization
are completely electronic means for correcting image shake. As the
shaky
image hits the CCD chip, these systems reposition the active area of
the
chip (the location on the chip that the image is read from) to
compensate
for it, by re-addressing the area of the chip that they're reading
from.
If you've seen Rocky & Bullwinkle (a US cartoon involving a
moose and
a squirrel), think of Bullwinkle running back and forth with the bucket
of water to catch Rocky after Rocky jumps from the high diving board
(of
course, Bullwinkle winds up in the water, but that's another story).

The EIS/DIS controllers look for motion vectors in the image
(typically
a widespread displacement of the entire image) and then decide how to
"reposition"
the image area of the chip under the image to catch it in the same
place.
The actual repositioning is done in one of two ways: one is to enlarge
(zoom) the image digitally, so that the full raster of the chip isn't
used.
The controller can then "pan and scan" within the full chip raster to
catch
the image as it moves about. The other is to use an oversize CCD, so
that
there are unused borders that the active area can be moved around in
without
first zooming the image.

The zoom-style pan 'n' scanner can be detected quite simply:
if the
image zooms in a bit when EIS/DIS is turned on, then a zoom-style pan
'n'
scanner is being used. Unfortunately, such methods reduce resolution,
often
unacceptably.

All EIS/DIS systems suffer from several problems. One is
that, because
the actual image is moving across the face of the chip, image shakes
induce
motion blur. Even though the position of an image may be perfectly
stabilized,
you can often notice a transient blurring of the image along the
direction
of the shake. Sometimes it's quite noticeable. To get around this,
many
EIS/DIS systems close down the shutter a bit to reduce blur. This
reduces
light gathering capability. You can't have everything, you know.

Another problem is that the motion-vector approach to
stabilization
can be easily fooled. If the area of the image being scanned doesn't
have
any contrasty detail that the processor can lock onto, the
stabilization
can hunt, oscillate, or bounce. This looks like a mini-earthquake on
the
tape, and it can occur at the most annoying times.

Also, the stabilization can work too
well. Often when one starts
a slow pan or tilt with EIS/DIS engaged, the system will see the start
of the move as a shake, and compensate for it! Eventually, of course,
the
stabilizer "runs out of chip" and resets, and the image abruptly
recenters
itself.

The big advantage of EIS/DIS is that it's cheap.

What's optical stabilization?

Optical stabilization such as "SteadyShot" is descended from Juan de la
Cierva's 1962 Dynalens design, a servo-controlled fluid prism used to
steer
the image before it hits the CCDs (in the '60s, of course, it steered
images
onto film or onto tubes!). In the late '80's and early '90's, Canon and
Sony updated this technology for use in consumer gear, and it worked so
well that Canon now offers a SteadyShot attachment for some of their
pro/broadcast
lenses.

The fluid prism is constructed of a pair of glass plates
surrounded
by a bellows and filled with fluid so that the entire assembly has a
refractive
index comparable to a glass prism. The angle of the prism is changed
by
tilting the plates; one plate can be rotated vertically, moving the
image
up or down, and the other rotates horizontally, steering the picture
right
or left.

Rotation rate sensors detect shake frequencies and tilt the
front and
back plates appropriately. Position sensors are also used so that in
the
absence of motion the prism naturally centers. The position sensors
also
detect when the prism is about to hit its limit stops, and reduce the
corrections
applied so that shake gradually enters the image instead of banging in
as the prism hits its limits.

Optical stabilization of this sort is expensive, tricky to
manufacture
and calibrate, and must be tuned to the lens. Adding a wide-angle or
telephoto
adapter to a SteadyShot lens screws up SteadyShot; the processor
doesn't
know about the changed angle of view (all it knows is the current zoom
setting) and thus over- or under-compensates for shake.

But for all that it works brilliantly: because the image is
stabilized
on the face of the CCDs, there is no motion blur; because rate sensors
are used, the system isn't fooled by motion in the scene or by lack of
detail; because a physical system has to move to reposition the image,
there are no instantaneous image bounces or resets as can happen with
EIS/DIS.

[It's interesting to note that on the XL-1, Canon added
image motion-vector
detection to the rate gyros on their optical stabilizer. As a result,
the
system seems to "stick" on slow pans and tilts just like an EIS/DIS
system,
although the recovery is more fluid and less jarring. On the other
hand,
it really does a superb job on handheld lockdowns.]

What about Steadicam/GlideCam?

These mechanical stabilizers work by setting up the camera so that it
has
large rotational moments of inertia, but little reason to want to
rotate:
the camera is mounted on an arm or pole that's gimballed at its center
of gravity or just above it. The gimbal mount is either handheld, or
attached
to an arm, often articulated and countersprung, mounted on a body
bracket
or vest. One steers the camera by light touches near the gimbal;
otherwise
it just tends to float along in whatever attitude it's already at. The
trick is in getting it into an attitude that makes nice pictures,
stopping
it there, and then not disturbing it.

These systems work very well, but require a lot of practice
for best
results. It's very easy to oversteer the camera, and off-level
horizons
are a trademark of suboptimal Steadicam skills. The handheld systems
can
also be surprisingly fatiguing to use for extended periods.

I find that the Steadicam JR is also a bit wobbly; its
plastic arms
aren't especially rigid and the whole thing tends to vibrate a bit.
Fortunately,
the wiggles that get through the JR are neatly compensated for by
SteadyShot
in the VX1000, resulting in buttery-smooth moving camera shots
(complete
with off-level horizons!).

When do I use what kind of image stabilization?

Try it; see if it works; if it helps, then use it.

I tend to leave optical stabilization on most of the time.
I'll turn
it off when using the wide-angle adapter, or when using the camera on
a
tripod and needing to conserve power.

If I'm planning to do any significant camera motion during a
shot, and
I don't have a wheelchair, dolly, car, airplane, or helicopter
available
(there's never
a helicopter around when you need one...), I'll use
the Steadicam JR. Depending on the roughness of the ride in the
aforementioned
conveyances, and space allowing, I'll use Steadicam there, too (Mikko
Wilson writes that in general, you don't want to be using Steadicams
in
helicopters. He's right--you really should use Tyler mounts or
Wescam-type rigs--but for shooting sideways out of a Schweizer 300C
with a Handycam on no budget, it seems to work fairly well. Just
remember: safety first--something that, by the evidence, many camera
ops and camera pilots fail to remember).

And don't forget that other, less glamorous form of
stabilization: the
tripod. Tripods work really, really well. Try one sometime, you'll
like
what it does for your image!

Copyright (c) 1998-2008 by Adam
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